Perceived air quality and particulate matter pollution based on field survey data during a winter period.

Outdoor air pollution and especially particulate matter pollution is a major environmental health issue that raises concerns of scientists and policy makers. This study focuses on air quality perception in relation to particulate matter in order to find potential patterns. Field questionnaire-based surveys were conducted among pedestrians on two central sites in the city of Athens, Greece, during the winter period while particulate matter of 10 µm or less in diameter (PM10) were concurrently measured on-site at 1-min resolution. The participants were asked to evaluate the dust and the overall pollution-related air quality based on 5-point bipolar scales. Air quality perception patterns were explored considering PM10 concentration, meteorological and thermal conditions, and subjective variables including gender, age, smoking status, and health status. An effect of PM10 on dust perception was identified, suggesting that dusty air quality conditions are reported more frequently when particulate concentration increases. Health status, exposure time, smoking status, and gender were found to affect air quality perception. Participants experiencing health symptoms, exposed to outdoor conditions for more than 30 min, smokers, and females were more likely to report unfavorable air quality conditions. The comparison with the results of a previous study obtained using air pollution station data confirmed the dependence of air quality perception on participants' characteristics and particularly on their health status. Ordinal logistic regression models showed that for pedestrians who were neither smokers nor experiencing health symptoms and were exposed to outdoor conditions for more than 30 min, a PM10 concentration around 64 µg·m-3 could be a threshold, to perceive dusty air quality conditions.

Testing and application of simple semi-analytical models for soil temperature estimation and prediction in environmental assessments.

The ability of various semi-analytical models to predict soil temperature profiles in an experimental plot during a 16-year monitoring study for soil depths up to 120 cm is evaluated. The models are developed from an analytical model by replacing the steady-state soil temperature with easily obtained hourly and daily average temperature values. Such values include the hourly air temperature, the daily average air temperature, the hourly soil temperature of selected soil depths from three daily observations, the daily average of the soil temperature profile and the hourly soil temperature for the bottom depth. The performance evaluation results show that, in principle, all models exhibit high correlation (R2 values in the range 0.85-0.97), indicating a very good agreement between measured and predicted values. In addition, error statistics reveal that the best performance in terms of Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) is the model based on the daily average of the soil temperature profile with MAE values in the range of 0-0.4°C and RMSE values in the range of 0.1-1.5°C.

Air quality perception of pedestrians in an urban outdoor Mediterranean environment: A field survey approach.

Perception plays a significant role on people's response to preventive measures. In the view of public awareness, the aim of this study was to explore factors that affect air quality perception and to reveal its potential patterns. Air quality perception of individuals, in terms of dust and overall air quality, was examined in relation to air pollutants concentrations, meteorological variables, personal characteristics as well as their thermal sensation and health condition. The data used were obtained from environmental measurements, in situ and from stations, and questionnaire surveys conducted in an outdoor urban Mediterranean area, Athens, Greece. The participants were asked to report their air quality perception and thermal sensation based on predefined scales. A thermal index, Physiological Equivalent Temperature (PET), was estimated to obtain an objective measure of thermal sensation. Particulate matter (PM10) and nitrogen oxide (NO) were associated with dust perception. Nitrogen oxides (NOx) and carbon monoxide (CO) were associated to air quality perception. Age, area of residence, health symptoms and thermal sensation also affected the perception of air quality. Dusty or poor air quality conditions were more likely to be reported when pollutants' concentrations were increased. Younger people, participants residing in the city center, experiencing health symptoms or warm thermal sensation showed a trend towards reporting more unfavorable air quality conditions.

Summertime measurements of benzene and toluene in Athens using a differential optical absorption spectroscopy system.

In this paper, measurements of benzene, toluene, p,m-xylene, ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2) made using the differential optical absorption spectroscopy (DOAS) technique during a 4-month period of summer 2000 (June-September) in Athens, Greece, are presented. An assessment of benzene mean value concentrations during this 4-month period exceeded 10 microg/m3, which is 2 times greater than the average yearly limit proposed by European authorities. Toluene measurements present mean values of approximately 33 microg/m3. Benzene and especially toluene measurements are highly correlated with NO2 and anticorrelated with O3. High values of benzene, NO2, and toluene are also correlated with winds from the southeast section, an area of industrial activity where emissions of volatile organic compounds (VOCs) have been recorded in previous studies. O3 is correlated with winds from the south-southwest section affected by the sea breeze circulation. Diurnal variations of O3, NO2, and SO2 concentrations are compatible with measurements from the stations of the Ministry of Environment's network. Outliers are combined with weak winds from the south-southwest. As far as p,m-xylene measurements are concerned, there is a poor correlation between gas chromatography (GC) and DOAS Opsis measurements, also observed in previous relevant campaigns and eventually a criticism in the use of the DOAS Opsis model for the measurement of p,m-xylene.